Mirror, reflector, and the like



Sept. 18, 1928. 1,685,032 C. A. PARSONS i MIRROR, REFLECTomAND THE LIKE Filed' Deo. 27, 192s Patented Sept. 18, 1928.

UNITED s'rA'rss ear irrita MIRROR, REFLRCTOR, AND THR LiKE.

Application led December 27, 1923,v Serial No.

683,018, andn'in G-reat Britain January 27, 1923.

This invention relates to searchlight mir-springe, or series of springs, side by side',

rors, reflectors and thev like receiving the rays directly from a source of light and projecting them in the form of a beam, suchmir rors, reflectors or the like being hereinafterA referred to as searchllght projector mirrors.

Y The primary object of the present invention is to modify the shape of the beamrof light reflected from such mirrors; for example, in many cases it is desirable to secure a fan-like beam of sufficient lateral divergence to increase greatly the field of illumination in a horizontal direction while preserving ther concentrationin the vertical direction.

I am aware that with a similar'obj ectparabola-ellipse mirrors have been constructed- Y to give a wide-angle fan-like beam, a. common angle of divergence being 15, and I am also aware that parabolic mirrorsfsplit down a diameter and hinged have been used to give two beams, each in itself parallel .but adjustable at different angles in relation to one another. Y

According tothe present invention, means hereinafter .described and particularly pointed out in the claims are provided whereby the shape of the beam is modified by elastic deformation of the mirror. y y Y For example, taking the case of a barabolic silvered glass reflector giving a nearly parallel beam or cone of light of a small divergenceof about 2 orso depending on the diameter of the crater of the positive carbon, it is possible by elastic deformation of the glass to modify the beam to a fan-like form of the nature referred to above. Referring to the accompanying drawings l Figure l is a rear elevation of a mirror according to one form of the invention;

Figure 2 being a cross-section on the line 2-2 ofFigure l, as seen in the direction of Y the arrows;

Figure 3 is a similar cross-section showing a modification of the invention.

In carrying the invention into effect acv cording to the illustrative form shown, the silvered glass mirror, a, of parabolic form, is supported centrally jin a frame, b, of angle section by a series of flexible spring clips, c,y

in theV usual manner in order to guard the mirror from shock.

The mirror on the horizontal centre linel is secured to the opposite ends ofy one dis-V torting member or beam, d, by means of a member, f', carrying a centralizing tube, f?,

threading through the axialaperture of the central member, cZ, and also through the axial aperture of a compensating plate, h, interposed between the central circular mem-V bers, d and f.' The compensating platejt, is formed on one surface with two cular member, while two diametrally-disr posed ball-ended screws, g', g, passthrough the circular central member, df, and bear on; the other face vof the plate, 71,; l The com-v bined effect ofvthese beams produces dis-V tortion inthe mirror when the ball-ended screws, g, g, are tightened against the com` pensating plate, L, causing the mirror to be t diametra'lly-disposed ridges, L, tf, bearing onthefcir- .pushed with equal forces at the ends of itsl v vvertical diameter and pulledl simultaneously with vequal forces towards the Yback at the ends of its horizontal'diam'eter so as thereby tochange the horizontal'section toa slightly greater focal length and the vertical mirror beyonda safe amount of stress.

' When wide angles of divergence in a horizon- Y tal plane are desired the lmirror is preferablyV made of very thin glass; as an instance, a 20 diameter mirror may der 1/8 thickness. v v Y lt will be seen from Figures l and 2 that a mirror has beenillustrated of a pattern suitable for use with an arc lamp of the horizontal type inwhich the carbons pass through a hole in the centre ofthe mirror. In cases' section` to a slightly shorter focal length.v Thus',

of divergence accordbe made of glass of un- Y where thishole is not required, the distorting members may be modified and actuated by one iov ball-ended screw centrally located, thus renderinga` compensating plate unnecessary.

Thus, as shoivnin Figure 3, the mirror is Without ai central aperture, while the tivo beams, d?, f3, are similar to the beams, d, j', oi" Figures l and 2, and are' actuated by the singlecentrally-disposed ball-ended srreiv, g2,

the compensating plate, labeing omitted. The

screw, g2, thus serves as a single instrumentality whereby the desired distorting forces may be simultaneously applied to the mirror at f about the ends of two diameters mutually at right angles.

The invention is not only applicable to silvered glassiniirors but also' to mirrors lor other material having the necessary elastic properties.

Having now vdescribed my invention, what I Y claim as new and desire to secure by Letters Patent is 1. The combination of a searclilight projector mirror; means contacting ivitli said mirror for applying opposite forces to points thereof concentrated at about the ends of tirediameters of said mirror mutually at right anl-gles differentially to alter the curvature of said mirror along Vsaid diameters by elastic Vdeformation thereof and mechanical means for simultaneously actuating said torce-apsaid mirror, other means forapplying distorting forces likewise parallel to the axis of said mirror concentrated at about the ends ofV a diameterof said iniri'orat rightangles to said first-mentioned diameter and mechanical jmeansfor simultaneously actuating said distorting force lapplying means. l M

5. The combination of a searchlight pro- ]ector mirror, means contacting with said mirror for applying distorting forcesparallel to the axis of said mirror conffentrated at about rthe ends of a diameter of said mirror, other means contacting With said mirrorl for applyn ing distortin gforces equal and opposite to said first-mentioned 'distorting vforces concentrated at about the ends of a diameter oit said mirror at right angles to said Erst-mentioned diameter-and mechanical means for simultaneously Y actuatingv said distorting vforce vapplying means. n Y

, 6. The `combination of asearclilight` rovjector mirrora frame, means'for attaciing said mirror to said fram@4 elf-contained means other than said frame and acting independ ently thereof forv positivelyr modifying the curvature of said mirror by elasticy deformation thereof, and yieldable means connecting said mirror and said self-containedmeans.

7. vThe combination `of Va searchlightlirojector mirroi7 a frame,.yieldable means for at-l taching said mirror to 4said frame, self-contained means other than said frame and acting independently thereof for positivelyT modifying` the curvature of said mirror byelastic def- Y orinatioii thereof, yield'able: means connecting said mirror and saidself-contanied means.

Y In testimony whereof I have name to this specification.

CHARLES ALGERNON masons.

signed my 

